This invention relates generally to fire extinguishing sprinkler heads and, more particularly, to an automatically extendable sprinkler head that can be mounted substantially flush with the ceiling of a fire protected enclosure.
Sprinkler systems are used extensively to provide automatic fire protection for residential, commercial and public buildings. A major sprinkler heads they employ. The sprinkler heads generally include rather unattractive, temperature responsive structures that extend a substantial distance below the ceilings of enclosures in which they are installed. In addition to presenting a generally unaesthetic appearance, projecting sprinkler heads create shadows that are undesirable in many types of structures.
In the interest of improving the appearance of sprinkler systems, various types of so-called recessed sprinkler heads have been disclosed. Such heads generally include a valve and deflector assembly that is movably mounted within a housing adapted for flush mounting in a ceiling. In response to elevated temperature, a fusible retaining element melts to release the valve and deflector assembly which is moved by water pressure into operational position below the recessed housing. In one type of flush mounted sprinkler head, the recessed valve and deflector assembly is retained in position only by a fusible alloy. Examples of such a sprinkler head are disclosed in U.S. Pats. Nos. 3,067,823 and 3,198,258. Because the full force produced by the system's water pressure is restrained by the fusible alloy, sprinkler heads of this type do not Provide the quick response and reliability that is required for a fire protection system. Other prior recessed sprinkler heads employ various types of lever arrangements to reduce the force that is restrained by the fusible alloy. Heads of that type are disclosed in U.S. Pats. Nos. 2,211,399; 3,459,266; and 3,714,989. Although improving response and reliability, the lever assemblies are bulky, unattractive and costly. U.S. Pat. No. 3.080,000 discloses another recessed sprinkler head utilizing a modified assembly for reducing the force restrained by the fusible alloy. The sprinkler head disclosed in that patent employs bowed struts that are connected mechanically in parallel with the fusible alloy. As with the above-described lever assemblies, the bowed strut assembly is bulky and unattractive and adds substantially to the manufacturing costs of the sprinkler head. Another recessed sprinkler head is disclosed in U.S. Pat. No. 4,465,141. Although, the head therein disclosed offers improved performance, the need exists for reliable sprinkler heads of reduced cost.
The object of this invention, therefore, is to provide a reduced cost fire sprinkler head that can be mounted substantially flush with the ceiling of a protected enclosure and which will quickly, automatically and reliably move into operational position below the ceiling in response to a predetermined rise in ambient temperature.